A projector for automatically adjusting images projected onto a screen includes a detecting module for detecting a propagation time for projected ultrasonic waves sent by the projector to be echoed back by the screen and received by the projector, a processing module for calculating a projection distance between the projector and the screen based on the propagation time, and outputting a focal length signal corresponding to the projection distance, an optical module, and an adjusting module for adjusting a local length of the optical module according to the focal length signal. A related method is also provided.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for automatically adjusting images projected onto a screen, comprising: projecting ultrasonic waves to the screen and receiving ultrasonic waves reflected by the screen; detecting a propagation time it takes for the projected ultrasonic waves to be received as the reflected ultrasonic waves; calculating a projection distance between the projector and the screen based on the propagation time, and outputting a focal length control signal corresponding to the projection distance; and driving an optical module to adjust a focal length of the optical module according to the focal length signal.
2. The method as claimed in claim 1 , wherein the step of projecting ultrasonic waves and receiving the ultrasonic waves reflected by the screen comprises: generating an ultrasonic signal; converting the ultrasonic signal to the projected ultrasonic waves; projecting the ultrasonic waves; receiving the ultrasonic waves reflected by the screen; and converting the ultrasonic waves received to a received ultrasonic signal.
3. The method as claimed in claim 2 , further comprising: modulating the generated ultrasonic signal.
4. The method as claimed in claim 3 , further comprising: amplifying the modulated ultrasonic signal.
5. The method as claimed in claim 4 , further comprising: demodulating the received ultrasonic signal.
6. The method as claimed in claim 5 , further comprising: amplifying the received ultrasonic signal after demodulation.
7. The method as claimed in claim 6 , further comprising: identifying the received ultrasonic signal after amplification.
8. A projector, comprising: a detecting module for computing a propagation time by transmitting ultrasonic waves to a screen and receiving ultrasonic waves reflected by the screen; a processing module for calculating a projection distance between the projector and the screen based on the propagation time, and outputting a focal length signal corresponding to the projection distance; an optical module; and an adjusting module for adjusting a focal length of the optical module according to the focal length signal.
9. The projector as claimed in claim 8 , wherein the processing module also outputs a lens position signal corresponding to the projection distance between the projector and the screen.
10. The projector as claimed in claim 9 , wherein the optical module comprising a lens, the lens position signal is output to the adjusting module, and the adjusting module is configured for driving the optical module to adjust a position of the lens according to the lens position signal.
11. The projector as claimed in claim 8 , wherein the detecting module comprises a timer for detecting the propagation time for transmitting the ultrasonic waves to the screen and receiving the ultrasonic waves returned from the screen.
12. The projector as claimed in claim 8 , wherein the detecting module comprises a generating unit for generating an ultrasonic signal, a transmitter for converting the ultrasonic signal to the ultrasonic waves that are transmitted, and a receiver for converting the ultrasonic waves received to a received ultrasonic signal.
13. The projector as claimed in claim 12 , wherein the detecting module further comprises a modulating unit for generating a carrier signal, which is modulated by the ultrasonic signal to form a modulated ultrasonic signal, and a demodulating unit for demodulating the received ultrasonic signal.
14. The projector as claimed in claim 13 , wherein the detecting module further comprises a first amplifying unit coupled between the modulating unit and the transmitter for amplifying the modulated ultrasonic signal.
15. The projector as claimed in claim 14 , wherein the detecting module further comprises a second amplifying unit coupled between the receiver and the demodulating unit for amplifying the received ultrasonic signal.
16. The projector as claimed in claim 15 , wherein the detecting module further comprises an identifying unit for identifying the received ultrasonic signal after demodulation.
17. The method as claimed in claim 1 , further comprising: driving the optical module to adjust a lens position corresponding to the projection distance.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
April 17, 2007
October 5, 2010
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